Massively parallel lithography with two-dimensional pen arrays

ABSTRACT

Massive parallel printing of structures and nanostructures at high speed with high resolution and high quality using two dimensional arrays comprising cantilevers and tip-based transfer of material to a surface. The array is designed so only tips touch the surface. This can be accomplished by long tips and bent cantilevers and alignment. An article comprising: a two-dimensional array of a plurality of cantilevers, wherein the array comprises a plurality of base rows, each base row comprising a plurality of cantilevers, wherein each of the cantilevers comprise tips at the cantilever end away from the base, wherein the number of cantilevers is greater than 250, and wherein the tips have an apex height relative to the cantilever of at least four microns, and a support for the array. Combinatorial arrays and bioarrays can be prepared. The arrays can be manufactured by micromachining methods.

RELATED APPLICATIONS

This application claims the priority benefit of U.S. provisionalapplication Ser. No. 60/792,950 filed Apr. 19, 2006 to Mirkin et al.,which is hereby incorporated by reference.

FEDERAL FUNDING STATEMENT

The present invention was developed with use of federal funding from thefollowing grant agencies and grant numbers: Air Force Office ScientificResearch, AFOSR FA9550-05-1-0348; AFOSR 28065-3/W91INF-04-1-071; andNational Institutes of Health NIH DPI 0D000285-02. The federalgovernment reserves rights in the invention.

BACKGROUND

Dip-Pen Nanolithographic® (DPN)® printing has been developed in variousembodiments as a scanning probe-based technique that uses, at least insome embodiments, a coated sharp tip such as an atomic force microscope(AFM) tip to pattern surfaces on, for example, the sub-50 nm to manymicrometer length scale (see, for example, Piner et al. Science 283,661-663 (1999)). This novel printing technique in its variousembodiments can combine soft matter compatibility with the highresolution of scanning probe and AFM methods, thereby affording uniqueopportunities to use micro-and nano-patterned substrates in a variety offields ranging from molecular electronics to biomedicine. However, anobstacle in commercially utilizing DPN printing for some applicationshas been its relatively low throughput (see, for example, Hong et al.Science 288, 1808 -1811 (2000); Salaita et al. Small 1, 940-945 (2005)),a limitation associated with the field of scanning probe lithography ingeneral (see, for example, Gates et al. Chem. Rev. 105, 1171-1196(2005); Tseng et al., J. Vac. Sci. & Tech. B 23, 877-894 (2005)). Inparticular, the DPN method is generally used as a serial method ratherthan a parallel method, and the exponential complexity and cost arisingfrom individually addressed feedback systems can constrain itsaccessibility and the rate of patterning. Therefore, a commercial needexists to improve throughput of the DPN method while maintaining itssimplicity.

In many cases, the lithography has been to date carried out with one penon one instrument to transfer a patterning compound or material to thesurface. However, one approach has been to use multiple pen systemswherein multiple pens operate in parallel on one instrument. Forexample, WO 00/41213 to Mirkin et al. describes use of a plurality oftips with a single device, referring to U.S. Pat. No. 5,666,190 to Quateet al. (Stanford) for descriptions of cantilever arrays andnanolithographic application. In addition, WO 01/91855 to Mirkin et al.describes working examples with a plurality of tips, wherein a lineararray of eight tips were obtained from a larger wafer block of tips andaffixed to a ceramic tip carrier and mounted to an AFM tip holder withepoxy glue.

Salatia et al. Small, 2005, 1, No. 10, 940-945 describe parallelprinting with 250 pen arrays, 26 pen arrays, and blocks of 26 penarrays. U.S. Pat. No. 6,642,129 to Liu et al. describes parallelindividually addressable probes for nanolithography including lineararrays and two dimensional arrays. The review by Ginger et al. Angew.Chem. Int. Ed. 43, 30-45 (2004)) describes 10,000 pen systems.

Massively parallel nanoarray platforms have been noted including asystem with 1.2 million pens per four inch diameter wafer. See, forexample, Demers et al., Genetic Engineering News, vol. 23, no. 15, Sep.1, 2003, 32.

Parallel probes have also been developed by IBM. See for example,Vettiger et al., IBM J. Res. Dev. 2000, 44, 323; King et al., J.Microelectromech. Syst. 2002, 11, 765. See also U.S. Pat. No. 5,835,477to Binnig et al.

However, a need yet exists to improve this approach in view of, forexample, the difficulties associated with fabricating large numbers ofpens in a confined space including in two dimensional arrays and inadapting the pens to a larger or customized instrument to control theprinting process. For example, leveling and alignment of massive numbersof cantilevers and tips is an engineering challenge. The pens must beefficiently produced so that as many of the pens as possible are usable.Fabrication should be convenient, and the pens should be robust forcommercial use with a variety of patterning compounds and materials.High rates of patterning structures, including nanostructures, areneeded at high resolution and registration. While multiple pen systemshave been used for patterning, the number of dots generated by contacthas typically been the same as the number of pens. Otherwise, noregistration exists between the two sets of dots. A need exists tobetter demonstrate the writing capabilities of large pen systemsincluding better registration and alignment.

SUMMARY

The present invention comprises a plurality of different embodiments.For example, one embodiment comprises a two-dimensional array of aplurality of cantilevers, the cantilevers comprising tips at thecantilever ends, wherein the array is adapted to prevent substantialcontact of non-tip components of the array when the tips are broughtinto contact with a substantially planar surface.

Another embodiment comprises an article comprising: (i) atwo-dimensional array of a plurality of cantilevers, wherein the arraycomprises a plurality of base rows, each base row comprising a pluralityof cantilevers extending from the base row, wherein each of thecantilevers comprise tips at the cantilever end away from the base row,wherein the array is adapted to prevent substantial contact of non-tipcomponents of the array when the tips are brought into contact with asubstantially planar surface; and (ii) a support for the array.

Another embodiment comprises an article comprising: (i) atwo-dimensional array of a plurality of cantilevers, wherein the arraycomprises a plurality of base rows, each base row comprising a pluralityof cantilevers extending from the base row, wherein each of thecantilevers comprise tips at the cantilever end away from the base row,wherein the array is adapted to prevent substantial contact of non-tipcomponents of the array when the tips are brought into contact with asubstantially planar surface.

In another embodiment, the invention provides an article comprising: atwo-dimensional array of a plurality of cantilevers, wherein the arraycomprises a plurality of base rows, each base row comprising a pluralityof cantilevers, wherein each of the cantilevers comprise tips at thecantilever end away from the base, and wherein the tips have an apexheight relative to the cantilever of at least, for example, fourmicrons, and a support for the array.

Another embodiment provides an article comprising: a two-dimensionalarray of a plurality of cantilevers, wherein the array comprises aplurality of base rows, each base row comprising a plurality ofcantilevers, wherein each of the cantilevers comprise tips at thecantilever end away from the base, and wherein the tips are coated withmetal on the tip side of the cantilever and the cantilevers are bent atan angle of at least, for example, 10° from their base.

In another embodiment, the invention provides, for example, a method ofmaking an article, wherein the article comprises a two-dimensional arrayof a plurality of cantilevers, and a support for the array, the methodcomprising: (i) forming a two dimensional array comprising a pluralityof cantilevers comprising tips at their ends, wherein the cantileversare supported on a sacrificial support structure; (ii) forming an arraysupport comprising a plurality of base rows which are adapted forbonding to the two dimensional array comprising a plurality ofcantilevers; (iii) bonding the cantilevers to the base rows; and (iv)removing the support structure to release the cantilevers and form thearray.

Still further, another embodiment is a method comprising (1)micromachining a two dimensional array of cantilevers wherein thecantilevers are adapted to bond with a device which both supports thecantilevers and can also couple the cantilevers to an instrument formotion, and (2) bonding the cantilevers to the device.

Also provided are instruments comprising the two dimensional arrays andsupport structures and methods of building and using the instruments,including for fabrication of micron-scale and nanometer scalestructures.

Also provided are patterned substrates made from the arrays, devices,and instruments described herein.

Also provided are methods for fast patterning of nanostructuresincluding, for example, at least 100,000 or at least 1,000,000nanostructures per minute.

In a preferred embodiment, a solution is provided to the throughputlimitation through the use of novel 55,000-pen two-dimensional arrays inthe context of parallel DPN printing experiments for patterning, forexample, gold substrates with sub-100 nm resolution over large, squarecentimeter areas.

This new approach to parallel scanning probe lithography over largeareas can be contrasted with the work of others, which has focused onthe production of linear and two-dimensional cantilever arrays withindependent feedback systems, for the controlled oxidation (see, forexample, Minne et al. J. Vac. Sci. & Tech. B 14, 2456-2461 (1996); Minneet al. Appl. Phys. Lett. 73, 1742-1744 (1998)) or melting of anunderlying substrate (see, for example, Vettiger et al. IEEE Trans.Nanotechnology 1, 39-55 (2002)).

Notably, if feedback is not used, the lack of feedback systems coupledwith the ability to pattern a surface with molecule-based inks can makethis massively parallel DPN capability highly accessible and attractivefor high throughput nanofabrication experiments and commercializationinvolving, for example, both soft organic and hard inorganic materials.It can be particularly useful, for example, for fabricatingcombinatorial libraries of structures and duplicates of a desirednanostructure or particular type of nanopatterned substrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1. DPN patterning with 55,000 AFM cantilevers in parallel: (a)Optical micrograph of part of the 2D array of cantilevers used forpatterning. Inset shows an SEM image of the tips. (b) Large area SEMimage (left) of part of an 88,000,000 gold dot array (40×40 within eachblock) on an oxidized silicon substrate. A representative AFMtopographical image (right) of part of a block. (c) Representativeoptical micrograph (inset shows AFM image) of ˜55,000 features drawn inthe form of the face of the 2005 US five cent coins. The coin bears apicture of Thomas Jefferson, who helped develop the polygraph, amacroscopic letter duplicator that relies on an array of pens.

FIG. 2. A schematic diagram of the fabrication process for 2D cantileverarrays.

FIG. 3. Optical micrograph of part of a 2D 55,000 pen array. Insets areSEM images of the pen array from side view (top), and top view (bottom),respectively.

FIG. 4. (Left) Schematic diagram describing the procedure for mountingthe pen array. (Right) Photograph depicting the mounted pen array beinglocked into the exact position as the epoxy hardens.

FIG. 5. Optical image of a 2D pen array before and after making contactwith substrate.

FIG. 6. Dark Field optical micrograph of Au dots in 4×16 arraysdemonstrating the wide writing range of the 2D pen array.

FIG. 7. Optical micrograph of Au structures drawn in shape of thecharacters “2D DPN” on a silicon substrate. Inset (center) shows darkfield micrograph of one of the structures produced by one tip. Inset(right corner) is an SEM of these structures.

FIG. 8. Dark Field micrograph of a combinatorial Au structures. Each penproduced a set of structures divided into four quadrants comprising ninetriangles, four lines, 25 dots, and a “smiley face.” (inset) SEM showsone of these structures at high magnification.

FIG. 9. SEM image of pyramidal tip, where the measured tip apex heightis 8.8 microns and the base is 11.0 microns.

FIG. 10. Illustrating measurement of angle of cantilever bending anddistance of cantilever bending.

DETAILED DESCRIPTION Introduction/DPN Printing

References will be made in detail to the preferred embodiments, examplesof which are illustrated in the accompanying drawings. While the manyfacets of the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to those embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims and equivalents thereof.

Priority U.S. provisional application Ser. No. 60/792,950 filed Apr. 19,2006 to Mirkin et al. is hereby incorporated by reference.

For practice of the various embodiments described herein, lithography,microlithography, and nanolithography instruments, pen arrays, activepens, passive pens, inks, patterning compounds, kits, ink delivery,software, and accessories for direct-write printing and patterning canbe obtained from NanoInk, Inc., Chicago, Ill. Software includes INKCADsoftware (NanoInk, Chicago, Ill.), providing user interface forlithography design and control. E-Chamber can be used for environmentalcontrol. Dip Pen Nanolithography™ and DPN™ are trademarks of NanoInk,Inc.

The following patents and co-pending applications related todirect-write printing with use of cantilevers, tips, and patterningcompounds are hereby incorporated by reference in their entirety and canbe used in the practice of the various embodiments described herein,including inks, patterning compounds, software, ink delivery devices,and the like:

-   -   1. U.S. Pat. No. 6,635,311 to Mirkin et al., which describes        fundamental aspects of DPN printing including inks, tips,        substrates, and other instrumentation parameters and patterning        methods;    -   2. U.S. Pat. No. 6,827,979 to Mirkin et al., which further        describes fundamental aspects of DPN printing including software        control, etching procedures, nanoplotters, and complex and        combinatorial array formation.    -   3. U.S. patent publication number 2002/0122873 A1 published Sep.        5, 2002 (“Nanolithography Methods and Products Produced Therefor        and Produced Thereby”), which describes aperture embodiments and        driving force embodiments of DPN printing.    -   4. U.S. regular patent application, Ser. No. 10/366,717 to Eby        et al., filed Feb. 14, 2003 (“Methods and Apparatus for Aligning        Patterns on a Substrate”), which describes alignment methods for        DPN printing (published Oct. 2, 2003 as 2003/0185967).    -   5. U.S. regular patent application, Ser. No. 10/375,060 to        Dupeyrat et al., filed Feb. 28, 2003 (“Nanolithographic        Calibration Methods”), which describes calibration methods for        DPN printing.    -   6. U.S. Patent Publication 2003/0068446, published Apr. 10, 2003        to Mirkin et al. (“Protein and Peptide Nanoarrays”), which        describes nanoarrays of proteins and peptides;    -   7. U.S. Regular patent application, Ser. No. 10/307,515 filed        Dec. 2, 2002 to Mirkin et al. (“Direct-Write Nanolithographic        Deposition of Nucleic Acids from Nanoscopic Tips”), which        describes nucleic acid patterning (PCT /US2002/038252 published        Jun. 12, 2003).    -   8. U.S. Regular patent application, Ser. No. 10/320,721 filed        Dec. 17, 2002 to Mirkin et al. (“Patterning of Solid State        Features by Direct-Write Nanolithographic Printing”), which        describes reactive patterning and sol gel inks (now published        Aug. 28, 2003 as 2003/0162004).    -   9. U.S. Pat. Nos. 6,642,129 and 6,867,443 to Liu et al.        (“Parallel, Individually Addressible Probes for        Nanolithography”), describing active pen arrays.    -   10. U.S. Patent Publication 2003/0007242, published Jan. 9, 2003        to Schwartz (“Enhanced Scanning Probe Microscope and        Nanolithographic Methods Using Same”).    -   11. U.S. Patent Publication 2003/0005755, published Jan. 9, 2003        to Schwartz (“Enhanced Scanning Probe Microscope”).    -   12. U.S. patent application Ser. No. 10/637,641 filed Aug. 11,        2003, now published as 2004/0101469, describing catalyst        nanostructures and carbon nanotube applications.    -   13. U.S. patent application Ser. No. 10/444,061 filed May 23,        2003, now published as 2004/0026681 published Feb. 12, 2004, and        US patent publication 2004/0008330 published Jan. 15, 2004,        describing printing of proteins and conducting polymers        respectively.    -   14. U.S. patent application Ser. No. 10/647,430 filed Aug. 26,        2003, now U.S. Pat. No. 7,005,378, describing conductive        materials as patterning compounds.    -   15. U.S. patent application Ser. No. 10/689,547 filed Oct. 21,        2003, now published as 2004/0175631 on Sep. 9, 2004, describing        mask applications including photomask repair.    -   16. U.S. patent application Ser. No. 10/705,776 filed Nov. 12,        2003, now published as 2005/0035983 on Feb. 17, 2005, describing        microfluidics and ink delivery.    -   17. U.S. patent application Ser. No. 10/788,414 filed Mar. 1,        2004, now published as 2005/0009206 on Jan. 13, 2005 describing        printing of peptides and proteins.    -   18. U.S. patent application Ser. No. 10/893,543 filed Jul. 19,        2004, now published as 2005/0272885 on Dec. 8, 2005, describing        ROMP methods and combinatorial arrays.    -   19. U.S. patent application Ser. No. 11/056,391 filed Feb. 14,        2005, now published as 2005/0255237 published on Nov. 17, 2005,        describing stamp tip or polymer coated tip applications.    -   20. U.S. patent application Ser. No. 11/065,694 filed Feb. 25,        2005, now published as 2005/0235869 on Oct. 27, 2005, describing        tipless cantilevers and flat panel display applications.    -   21. US Patent publication 2006/001,4001 published Jan. 19, 2006        describing etching of nanostructures made by DPN methods.    -   22. WO 2004/105046 to Liu & Mirkin published Dec. 2, 2004        describes scanning probes for contact printing.

All references cited in 1-20 above are incorporated by reference and theteachings therein can be adapted for use with the various embodimentsdescribed herein.

DPN methods are also described in Ginger et al., “The Evolution ofDip-Pen Nanolithography,” Angew. Chem. Int. Ed. 2004, 43, 30-45,including description of high-throughput parallel methods.

Direct write methods, including DPN printing and pattern transfermethods, are described in for example Direct-Write Technologies,Sensors, Electronics, and Integrated Power Sources, Pique and Chrisey(Eds), 2002.

The direct-write nanolithography instruments and methods describedherein are particularly of interest for use in preparing bioarrays,nanoarrays, and microarrays based on peptides, proteins, nucleic acids,DNA, RNA, viruses, biomolecules, and the like. See, for example, U.S.Pat. No. 6,787,313 for mass fabrication of chips and libraries; U.S.Pat. No. 5,443,791 for automated molecular biology laboratory withpipette tips; U.S. Pat. No. 5,981,733 for apparatus for the automatedsynthesis of molecular arrays in pharmaceutical applications.Combinatorial arrays can be prepared. See also, for example, U.S. Pat.Nos. 7,008,769; 6,573,369; and 6,998,228 to Henderson et al.

Scanning probe microscopy is reviewed in Bottomley, Anal. Chem., 1998,70, 425R-475R. Also, scanning probe microscopes are known in the artincluding probe exchange mechanisms as described in, for example, U.S.Pat. No. 5,705,814 (Digital Instruments).

Two Dimensional Arrays

One embodiment is an article comprising: (i) a two-dimensional array ofa plurality of cantilevers, wherein the array comprises a plurality ofbase rows, each base row comprising a plurality of cantilevers extendingfrom the base row, wherein each of the cantilevers comprise tips at thecantilever end away from the base row, wherein the arrays are adapted toprevent substantial contact of non-tip components of the array when thetips are brought into contact with a substantially planar surface; and(ii) a support for the array. One particular embodiment is illustratedin the non-limiting working examples and figures.

One embodiment also provides an article comprising: (i) atwo-dimensional array of a plurality of cantilevers, wherein the arraycomprises a plurality of base rows, each base row comprising a pluralityof cantilevers, wherein each of the cantilevers comprise tips at thecantilever end away from the base, wherein the number of cantilevers isgreater than 250, and wherein the tips have an apex height relative tothe cantilever of at least, for example, four microns, and (ii) asupport for the array. One particular embodiment is illustrated in thenon-limiting working examples and figures.

Another embodiment provides an article comprising: a two-dimensionalarray of a plurality of cantilevers, wherein the array comprises aplurality of base rows, each base row comprising a plurality ofcantilevers, wherein each of the cantilevers comprise tips at thecantilever end away from the base, wherein the number of cantilevers isgreater than 250, and wherein the tips are coated with metal on the tipside of the cantilever and the cantilevers are bent at an angle of, forexample, at least 10° from their base. One particular embodiment isillustrated in the non-limiting working examples and figures.

Two-dimensional arrays of cantilevers are known in the art. For example,the two-dimensional array can be a series of rows and columns, providinglength and width, preferably substantially perpendicular to each other.The arrays can comprise a first dimension and a second dimension. Thetwo-dimensional array can be a series of one dimensional arrays disposednext to each other to build the second dimension. The two dimensions canbe perpendicular. The cantilevers can comprise a free end and a boundend. The cantilevers can comprise tips at or near the free end, distalfrom the bound end. The cantilevers of one row can point in the samedirection as the cantilevers on the next row, or the cantilevers of onerow can point in the opposite direction as the cantilevers on the nextrow.

The two-dimensional arrays can be fabricated by combining two parts,each part having a surface which is patterned in two dimensions andadapted to be mated with each other in the two dimensions.

One important variable is the fraction or percentage of the cantileversin the array which can actually function for the intended purposes. Insome cases, some cantilevers can be imperfectly formed, or can beotherwise damaged after formation. A cantilever yield reflects thispercentage of usable cantilevers. Preferably, the array is characterizedby a cantilever yield of at least 75%, or at least 80%, or at least 90%,or at least 95%, or more preferably, at least about 98%, or morepreferably at least 99%. In characterizing the cantilever yield,cantilevers at the ends of rows may be neglected which are damaged byprocessing of edges compared to internal cantilevers. For example, thecentral 75% can be measured. In many cases, the fabrication will bebetter done in the middle rather than the edge as edge effects are knownin wafer fabrication. Defect density can increase in some cases as onemoves from the center to the edge.

The array can be adapted to prevent substantial contact of non-tipcomponents of the array when the tips are brought into contact with asubstantially planar surface. For example, the cantilever arms shouldnot contact the surface and can be accordingly adapted such as by, forexample, bending. The tips can be adapted for this as well including,for example, long tips. Factors which can be useful to achieve thisresult include use of long tips, bending of the cantilever arms, tipleveling, row leveling, and leveling of the cantilevers in alldimensions. One or more combination of factors can be used.

The cantilever tips can be longer than usual in the art. For example,the tips can have an apex height relative to the cantilever of at leastfour microns on average, and if desired, the tips can have an apexheight relative to the cantilever of at least seven microns on average.In addition, tip apex height can be at least 10 microns, or at least 15microns, or at least 20 microns. No particular upper limit exists andtechnology known in the art and improving can be used. This long lengthcan help ensure that only tips are contacting the surface. Apex heightcan be taken as an average of many tip apex heights, and in general,apex height is engineered not to vary substantially from tip to tip.Methods known in the art can be used to measure tip apex heightincluding methods shown in the working examples.

In measuring parameters for the array, average measurements can be used.Average measurements can be obtained by methods known in the artincluding for example review of representative images or micrographs.The entire array does not need to be measured as that can beimpractical.

Tipless cantilevers can be used in some embodiments, although not apreferred embodiment. For example, one embodiment provides an articlecomprising: (i) a two-dimensional array of a plurality of cantilevers,wherein the array comprises a plurality of base rows, each base rowcomprising a plurality of cantilevers extending from the base row,wherein each of the cantilevers are tipless cantilevers, wherein thecantilevers are bent at an angle from their base.

In addition, the cantilevers can be bent including bent towards thesurface to be patterned. Methods known in the art can be used to inducebending. The cantilevers can be bent at an angle away from the base andthe support. The cantilevers can comprise multiple layers adapted forbending of cantilevers. For example, differential thermal expansion orcantilever bimorph can be used to bend the cantilevers. Cantileverbending can be induced by using at least two different materials.Alternatively, the same materials can be used but with differentstresses to provide cantilever bending. Another method is depositing onthe cantilever comprising one material a second layer of the samematerial but with an intrinsic stress gradient. Alternatively, thesurface of the cantilever can be oxidized. The cantilevers can be bentat an angle for example of at least 5° from their base, or at least 10°from their base, or at an angle of at least 15° from their base. Methodsknown in the art can be used to measure this including the methodsdemonstrated in the working examples. Average value for angle can beused. The cantilevers can be bent on average about 10 microns to about50 microns, or about 15 microns to about 40 microns. This distance ofbending can be measured by methods known in the art including themethods demonstrated in the working examples. Average distance can beused. The bending can result in greater tolerance to substrate roughnessand morphology and tip misalignment within the array so that for examplea misalignment of about ±20 microns or less or about ±10 microns or lesscan be compensated.

To facilitate bending, the cantilevers can comprise multiple layers suchas two principle layers and optional adhesion layers and can be forexample bimorph cantilevers. The cantilevers can be coated with metal ormetal oxide on the tip side of the cantilever. The metal is notparticularly limited as long as the metal or metal oxide is useful inhelping to bend the cantilevers with heat. For example, the metal can bea noble metal such as gold.

In preferred embodiments, the array can be adapted so that thecantilevers are both bent toward the surface and also comprise tipswhich are longer than normal compared to tips used merely for imaging.

The tips can be fabricated and sharpened before use and can have anaverage radius of curvature of, for example, less than 100 nm. Theaverage radius of curvature can be, for example, 10 nm to 100 nm, or 20nm to 100 nm, or 30 nm to 90 nm. The shape of the tip can be variedincluding for example pyramidal, conical, wedge, and boxed. The tips canbe hollow tips or contain an aperture including hollow tips and aperturetips formed through microfabrication with microfluidic channels passingto end of tip. Fluid materials can be stored at the end of the tips orflow through the tips.

The tip geometry can be varied and can be for example a solid tip or ahollow tip. WO 2005/115630 (PCT/US2005/014899) to Henderson et al.describes tip geometries for depositing materials onto surfaces whichcan be used herein.

The two dimensional array can be characterized by a tip spacing in eachof the two dimensions (e.g., length dimension and width dimension). Tipspacing can be taken, for example, from the method of manufacturing thetip arrays or directly observed from the manufactured array. Tip spacingcan be engineered to provide high density of tips and cantilevers. Forexample, tip density can be at least 10,000 per square inch, or at least40,000 per square inch, or at least 70,000 per square inch. The arraycan be characterized by a tip spacing of less than 300 microns in afirst dimension of the two dimensional array and less than 300 micronsin a second dimension of the two dimensional array. To achieve evenhigher density, the tip spacing can be, for example, less than about 200microns in one dimension and less than about 100 microns, or less thanabout 50 microns, in another dimension. Alternatively, the tip spacingcan be for example less than 100 microns in one dimension and a lessthan 25 microns in a second direction. The array can be characterized bya tip spacing of 100 microns or less in at least one dimension of thetwo dimensional array. In one embodiment, tip spacing can be about 70microns to about 110 microns in one dimension, and about 5 microns toabout 35 microns in the second dimension. There is no particular lowerlimit on tip spacing as fabrication methods will allow more dense tipspacing over time. Examples of lower limits include 1 micron, or 5microns, or 10 microns so for example tip spacings can be one micron to300 microns, or one micron to 100 micron.

The number of cantilevers on the two dimensional array is notparticularly limited but can be at least about three, at least aboutfive, at least about 250, or at least about 1,000, or at least about10,000, or at least about 50,000, or at least about 55,000, or at leastabout 100,000, or about 25,000 to about 75,000. The number can beincreased to the amount allowed for a particular instrument and spaceconstraints for patterning. A suitable balance can be achieved for aparticular application weighing for example factors such as ease offabrication, quality, and the particular density needs.

The tips can be engineered to have consistent spacing for touch thesurface consistently. For example, each of the tips can be characterizedby a distance D spanning the tip end to the support, and the tip arrayis characterized by an average distance D′ of the tip end to thesupport, and for at least 90% of the tips, D is within 50 microns of D′.In another embodiment, for at least 90% of the tips, D is within 10microns of D′. The distance between the tip ends and the support can befor example about 10 microns to about 50 microns. This distance cancomprise for example the additive combination of base row height, thedistance of bending, and the tip height.

Base row length is not particularly limited. For example, the base rowscan have an average length of at least about 1 mm. Average length forbase row can be, for example, about 0.1 mm to about 30 mm, or about 0.1mm to about 15 mm, or about 0.1 mm to about 5 mm, or about 0.5 mm toabout 3 mm.

The base rows can have a height with respect to the support of at leastabout 5 microns. This height is not particularly limited but can beadapted for use with the appropriate cantilever bending.

Cantilever force constant is not particularly limited. For example, thecantilevers can have an average force constant of about 0.001 N/m toabout 10 N/m, or alternatively, an average force constant of about 0.05N/m to about 1 N/m, or alternatively an average force constant of about0.1 N/m to about 1 N/m, or about 0.1 N/m to about 0.6 N/m.

A variety of methods can be used for bonding the cantilevers to thebase, and the methods are not particularly limited. Bonding methods aredescribed for example in Madou, Fundamentals of Microfabrication, 2^(nd)Ed., pages 484-494 which describes for example field-assisted thermalbonding, also known as anodic bonding, electrostatic bonding, or theMallory process. Methods which provide low processing temperature can beused. For example, the cantilevers can be bound to the base by anon-adhesive bonding. Bonding examples include electrostatic bonding,field-assisted thermal bonding, silicon fusion bonding, thermal bondingwith intermediate layers, eutectic bonding, gold diffusion bonding, goldthermocompression bonding, adhesive bonding, and glass frit bonding.

The cantilevers can be engineered so they are not adapted for feedbackincluding force feedback. Alternatively, at least one cantilever can beadapted for feedback including force feedback. Or substantially all ofthe cantilevers can be adapted for feedback including force feedback.For example, over 90%, or over 95%, or over 99% of the cantilevers canbe adapted for feedback including force feedback.

The cantilevers can be bound to the base by electrostatic binding.

The cantilevers can be made from materials used in AFM probes includingfor example silicon, polycrystalline silicon, silicon nitride, orsilicon rich nitride. The cantilevers can have a length, width, andheight or thickness. The length can be for example about 10 microns toabout 80 microns, or about 25 microns to about 65 microns. The width canbe for example 5 microns to about 25 microns, or about 10 microns toabout 20 microns. Thickness can be for example 100 nm to about 700 nm,or about 250 nm to about 550 nm. Tipless cantilevers can be used in thearrays, the methods of making arrays, and the methods of using arrays.

The cantilevers can be supported on the base rows, and the base rows inturn can be supported on a larger support for the array. The base rowscan extend from the larger support for the array. The array support canbe characterized by a surface area which is about two square cm or less,or alternatively about 0.5 square cm to about 1.5 square cm. The sizecan be adjusted as needed for coupling with an instrument.

Arrays can be adapted for passive pen or active pen use. Control of eachtip can be carried out by piezoelectric, capactive, or thermoelectricactuation, for example.

The arrays can be adapted for integration of tip coating and inkdelivery. For example, microfluidics can be used to control inking andcoating of the tips. Tips can be dipped into devices or ink can bedelivered directly through internal regions of the tip for hollow tipembodiments.

The tips can be coated with a patterning compound or ink material. Thecoating is not particularly limited; the patterning compound or inkmaterial can be disposed at the tip end. Patterning compounds andmaterials are known in the art of nanolithographic printing and includeorganic compounds and inorganic materials, chemicals, biologicalmaterials, non-reactive materials and reactive materials, molecularcompounds and particles, nanoparticles, materials that form selfassembled monolayers, soluble compounds, polymers, ceramics, metals,magnetic materials, metal oxides, main group elements, mixtures ofcompounds and materials, conducting polymers, biomolecules includingnucleic acid materials, RNA, DNA, PNA, proteins and peptides,antibodies, enzymes, lipids, carbohydrates, and even organisms such asviruses. The references described in the INTRODUCTION section describemany patterning compounds which can be used. Sulfur-containing compoundsincluding thiols and sulfides can be used.

The methods by which the tips can be coated can include for examplesolution dipping or vacuum evaporation, as well as the microfluidicmethods noted above. See U.S. patent application Ser. No. 10/705,776filed Nov. 12, 2003, now published as 2005/0035983 on Feb. 17, 2005.

Methods of Making Two Dimensional Arrays

Another embodiment comprises a method of making two dimensional arrays.For example, an embodiment comprises a method of making article, whereinthe article comprises a two-dimensional array of a plurality ofcantilevers, and a support for the array, the method comprising: (i)forming a two dimensional array comprising a plurality of cantileverscomprising tips at their ends, wherein the cantilevers are supported ona sacrificial support structure; (ii) forming an array supportcomprising a plurality of base rows which are adapted for bonding to thetwo dimensional array comprising a plurality of cantilevers; (iii)bonding the cantilevers to the base rows; and (iv) removing the supportstructure to release the cantilevers and form the array. Thenon-limiting working examples below provide one method for executingthese steps. See FIG. 2. In FIG. 2, the structure shown as“electrostatic binding” comprises patterned cantilevers (patterning notshown).

In some embodiments, tipless cantilevers can be fabricated.

The above description for the article comprising the two dimensionalarrays and support can be also applied to the methods making the twodimensional arrays. For example, in the method of making, the tips canbe adapted to prevent substantial contact of non-tip components of thearray when the tips are brought into contact with a substantially planarsurface. In the method of making, the tips can have an apex heightrelative to the cantilever of at least four microns, or at least sevenmicrons. In the method of making, the method can further comprise thestep of bending the cantilevers at an angle away from the support. Forexample, the method can comprise bending the cantilevers at an angle ofat least 10° away from the support. In the method of making, the tipscan have an apex height relative to the cantilever of at least fourmicrons, and wherein the cantilevers are bent at an angle away from thesupport. Also, in the method of making, the tips can have an apex heightrelative to the cantilever of at least seven microns, and wherein thecantilevers are bent at an angle of at least 10° away from the support.

Microfabrication methods are described extensively in for example Madou,Fundamentals of Microfabrication, 2^(nd) Ed., CRC Press, 2002; and VanZant, Microchip Fabrication, 5^(th) Ed., 2004.

In one part of the fabrication method, the two dimensional array can beformed by microfabrication and micromachining methods. The sub-productcan comprise the cantilevers supported on a sacrificial support whichcan be later removed before use. Microfabrication steps includingwafers, oxidation, patterning, etching, deposition, deep reactive ionetching (Bosch process) and other steps known for making cantilevers andtips can be used.

In another part of the fabrication method, an array support is formedwhich is adapted for bonding to the two dimensional array ofcantilevers. It can be also adapted for coupling the two dimensionalarray of cantilevers to the instrument for movement. Base rows can beformed which extend out from the surface of the array support andprovide support for the cantilevers upon fabrication.

The cantilevers can be bonded to the base rows. An example of a bondingmethod is electrostatic bonding.

The sacrificial support for the cantilevers can be removed to free up orrelease the cantilevers. Methods known in the art can be used to executethis step.

FIG. 2 from the working examples below illustrates a fabrication method,although the parameters and materials described therein can be modified.For example, the 200 nm layer of silicon oxide can be, for example, 100nm to 300 nm; the 950° C. can be for example 850° C. to 1050° C.; the 30minutes can be for example 15 minutes to 45 minutes; the 10 micronsquare openings do not have to be square can be for example 5 microns to15 microns; the 400 nm silicon nitride layer can be 200 nm to 600 nm, or300 nm to 500 nm; the 200 nm thick chromium layer can be for example 100nm to 300 nm; the 100 micron trenches can be for example 50 microns toabout 150 microns; the eight micron recesses can be for example 3microns to 13 microns so as to allow cantilever free movement; and thelike.

The working examples also provide a method for annealing pen arrays andthe parameters described therein can be modified. For example, the 5 nmTi adhesion layer can be 2 nm to 20 nm thick, and the 25 nm gold layercan be 5 rim to 100 nm thick. The annealing temperature can be forexample 150° C. to about 500° C., and the time for annealing can be forexample 30 minutes to 250 minutes.

Also provided is a method comprising (1) micromaching a two dimensionalarray of cantilevers wherein the cantilevers are adapted to bond with adevice which both supports the cantilevers and can also couple thecantilevers to an instrument for motion, and (2) bonding the cantileversto the device. The device can be called a handle wafer. One side is forbonding to the cantilevers. The other side is for coupling to a largerinstrument. The working examples below, for example, also illustratethis embodiment.

Leveling

Level can be carried out to provide leveling in each dimension of thetwo dimensional array. Leveling can help with adapting the array so onlytips contact the surface. The working examples below provide an exampleof leveling the cantilevers before the two dimensional array ofcantilevers are mounted onto an instrument. For example, gravity forcesand forces near to gravity forces can be used to level the cantileverson a sacrificial substrate. External force can be used. Other forces canbe used as needed for a particular two dimensional array. For example,forces can be about 0.2 nN/tip to about 2,000 nN/tip, or about 2 nN/tipor about 200 nN/tip, or about 20 nN/tip. The sacrificial substrate canbe made as flat as possible and practical for a given application.

The adhesive mounting method also allows one to improve leveling andavoid use of a feedback system if desired.

Optical microscopy can be used to facilitate leveling.

One embodiment provides a method comprising: (i) preparing atwo-dimensional array of a plurality of cantilevers, wherein the arraycomprises a plurality of base rows, each base row comprising a pluralityof cantilevers extending from the base row, wherein each of thecantilevers comprise tips at the cantilever end away from the base row,(ii) contacting tips of the array with a sacrificial substrate underpressure, (iii) forming an aligned array on the substrate, and (iv)attaching the aligned array to an instrument adapted for motion of thearray. The pressure can be generated either externally or with gravity.The attaching can be an adhesive or mechanical attaching. The method canfurther comprise removing the sacrificial substrate from the tips of thearray.

Mounting the Supported Two Dimensional Arrays on an Instrument

Mounting of arrays to the instrument can be achieved by one or moremechanisms operating individually or in combination. For example,mounting can be carried out with use of mechanical coupling, frictionfit or magnetic coupling. Adhesives and glues can be used including fastcuring and UV curing systems. Epoxy glue is described below includingits use as a gap filler or space filler.

Adhesive mounting can be used to couple the supported two dimensionalarrays to an instrument which provides x motion, y motion, z motion, orcombinations thereof including x,y,z motion. Motion is provided whichallows for high resolution patterning and high resolution such as foundwith for example scanning probe instruments.

The instrumentation can be also adapted to have the pens stand still andhave the substrates move in x, y, and/or z motion.

In a preferred embodiment, the bonding agent functions to both mount thetwo dimensional array to the instrument and also the facilitate levelingof the tip array.

Instrument

Also provided are instruments including printing and patterninginstruments, as well as nanolithography instruments. Instruments can beused which provide both imaging and patterning capability. While themethods and devices herein can be used with scanning probe and AFMinstrumentation, the instruments are not so limited. Dispensinginstruments and tools for delivering small scale amounts of materials tosurfaces are known. See for example U.S. Pat. Nos. 6,024,925; 6,087,274;5,981,733;

A preferred example of an instrument for lithography includingmicrolithography and nanolithography is the NScriptor™ from NanoInk(Chicago, Ill.). Commercial AFM instruments can be used.

An instrument is described in U.S. Pat. No. 7,008,769 to Henderson etal.

Using the Two Dimensional Arrays

DPN patterning is describe in the references noted above in theIntroduction Section and other references cited herein.

Substrates can be made with massive numbers of micron-scale ornanometer-scale structures, or nanostructures, formed at massively fastrates. For example, one important parameter is the rate at whichstructures can be formed. Using methods described herein, structures canbe formed at a rate of at least 100,000 per minute, or at least1,000,000 structures per minute, and even further at least 2,000,000structures per minute, and even further at least 3,000,000 structuresper minute, and even further at least 4,000,000 structures per minute,and even further at least 5,000,000 structures per minute, and evenfurther at least 10,000,000 structures per minute. For example,structures formed at fast rates can be dot features having a diameter offor example about 25 nm to about 500 nm, or about 50 nm to about 200 nm.The structures can be dots and circles, wherein the tip is not moved inthe X-Y direction during deposition of the patterning compound.

Other rate parameters can be used. For example, direct-writing can becarried out at a rate of at least 1.0 meter/min, or at least 3.3meters/min (for example, if the tips are moved at appropriate rates suchas for example a rate of 1 um/s). Patterning can be executed at10,000,000 square microns per hour. Rates can be in some casesdetermined by the rate of diffusion spreading for one pen withmultiplication by the number of pens.

A preferred embodiment comprises a method for direct-writenanolithography comprising: directly writing nanostructures at a rate ofat least 100,000 per minute, wherein the directly writing comprisescontacting a tip having a patterning compound thereon with a substrate.The rate can be at least 1,000,000 per minute, or at least 4,000,000 perminute. The nanostructures can comprise dots, lines, or substantiallycomplete circles. The nanostructures can comprise dots having diameterabout 50 nm to about 1,000 nm. The nanostructures can be separated by adistance between about 50 nm and about 1,000 nm, or about 100 nm toabout 750 nm.

Substrates can be coated and patterned with for example at least25,000,000 structures, or at least 50,000,000 structures, or at least75,000,000 structures, or at least 1,000,000 structures, or at least500,000,000 million structures, or at least 1,000,000,000 structures.

An important aspect is that the pattern formed on the substratesubstantially matches either (1) a pattern generated with software andmade with tip motion, or (2) the pattern of the array when the tips arenot moved over the surface.

An important embodiment comprises the elimination of a feedback system.This embodiment, having this eliminated, is a basic and novel feature.

The substrates for patterning can be single layer or multilayer. Theycan be solids including polymers, glasses, composites, silicon, mica,diamond, ceramics, metals, and various oxides and complex mixtures.

The ink-substrate combination can be selected to provide stablestructures. Stability can be enhanced by use of covalent bonding orchemisorption, or electrostatic attraction.

Arrays can be formed of inorganic, organic, or biological materialsincluding nanostructures such as viruses, proteins, carbon nanotubes,nanowires, dendrimers, fullerenes, and the like. Combinatorial arrayscan be formed. Each spot in the array can provide the same compositionor a different composition compared to the next spot.

Vibration isolation tables can be used. Environmental chambers can beused including nebulizer, real-time sensors for temperature and humiditycontrol, and heating and cooling fans. High resolution optics can beused. Independent three motor leveling can be used. Tip biasing can beused.

If AFM-like instrumentation is used, the mode can be contact mode,non-contact mode, or intermittent contact mode.

Another example of a use can be found in Lenhert et al, “MassivelyParallel Dip-Pen Nanolithography of Heterogeneous Supported PhospholipidMultilayer Patterns,” Small, 2007, 3, No. 1, 71-75, which is herebyincorporated by reference including FIGS. 1-4, experimental section, andnoting references cited therein. The instruments described herein can beused to control multi-bilayer stacking (FIG. 1); phospholipid patternsincluding fluorophore doping (FIG. 2); parallel writing of multiple inksincluding for testing membrane fluidity; and generation of fluorescentmicrographs.

The various embodiments are further illustrated by the followingnon-limiting examples.

WORKING EXAMPLES

Using conventional photolithographic techniques, a 55,000 pentwo-dimensional array was fabricated (pen yield >98%; pen spacing 90×20μm, FIG. 1 a). The challenge of leveling all 55,000 pens over asubstrate during a patterning experiment was overcome, without the needfor independent feedback on each tip. Several important parameters weredeveloped.

First, arrays of Si₃N₄ (or silicon rich nitride material) cantileverswith pyramidal tips were fabricated such that the tips are about threetimes larger than conventional silicon nitride AFM tips (the apex ofeach tip was 7.6±0.2 μm taller than its cantilever base).

Second, the cantilevers were bent at a ˜20° angle from their base bycoating them with 25 nm of Au (and 5 nm Ti adhesion layer) and thenannealing at 300° C. This curvature is a result of the different thermalexpansion coefficients of Si₃N₄ and Au (see, for example, Wenzler, etal. T. P. Rev. Sci. Instrum. 67, 4191-4197 (1996)). This arrayarchitecture leads to greater tolerance to the substrate morphology andinherent tip misalignment within the array (±10 μm misalignment can becompensated).

Third, gravity (˜20 nN/tip), instead of a complex set of feedbacksystems, was used to bring all of the tips in contact with a sacrificialsubstrate prior to use.

Finally, the tip array was locked into position with respect to thepiezo scanner head by taking advantage of the malleability of a rapidlycuring epoxy resin (see supplementary information). This alignmentprocedure was useful so all of the tips within the array could beengaged and disengaged in a deliberate and controlled fashion without afeedback system. Once engaged, the pen array can be used to directlywrite virtually any pattern of molecules on the underlying substrate andsimultaneously generate ˜55,000 duplicates.

To test the writing capabilities of the pen array, its cantilevers wereuniformly coated with 1-octadecanethiol (ODT) by vapor deposition andsubsequently used to pattern a 25 nm film of polycrystalline gold on anoxidized silicon substrate with a 5 nm Ti adhesion layer. Using ODT as achemical etch resist, the molecular patterns were developed into goldnanostructures, allowing the use of an optical or scanning electronmicroscope to characterize the patterns over large areas. In an initialexperiment, the 55,000 pen array was used to generate ˜88 million dotfeatures (each tip generating 1,600 100±20 nm dots in a 40×40 array) inless than 20 min (FIG. 1 b). Significantly, >99% of all the pens(excluding 1-2% of pens damaged during processing) are in operation. AFMand SEM images confirm that registry and alignment are maintained withinthe field of view of each tip and between tips as well. One can evengenerate very sophisticated structures using this approach along withintegrated software that controls the relative movement of the tip arrayover the underlying substrate. Indeed, the likeness of Thomas Jeffersonwas taken from a 2005 United States five cent coin and duplicated˜55,000 times at a pixel resolution of 80 nm (FIG. 1 c).

Materials. Gold substrates were prepared according to literatureprocedures. (Weinberger et al., Advanced Materials, 12, 1600 (2000);Zhang et al., Langmuir, 20, 962-968 (2004). 1-octadecanethiol (ODT)(98%) and 1-octanol (99%) were purchased from Aldrich Chemical Co.Fe(NO₃)₃9H₂O (99%) was purchased from Acros Chemicals, thiourea (ACSgrade) was purchased from Fisher Scientific, and ethanol (ACS/USP grade)was purchased from Pharmco Products Inc. 5-min epoxy gel was purchasedfrom Devcon and used as specified by the manufacturer. All chemicalswere used as received.

Fabrication of 55,000 Cantilever Arrays: The Microfabrication processused to generate the tips was designed to be simple and robust, whichaffords high yields and is amenable for future modifications (FIG. 2). A200 nm layer of silicon oxide was thermally grown (950° C., 30 min) on asilicon <100> wafer and lithographically patterned with 10 micron squareopenings at a spacing of 90×20 microns. The oxide patterns were thenused as an etch mask for an anisotropic silicon etch (37% KOH, 20 min)to form pyramidal tip molds in the silicon wafer. The oxide etch maskwas removed in buffered HF (6:6:1 H₂0:NH₄F:HF, 5 min), and a 400 nmthick thin film of Si₃N₄ was deposited using a low pressure, low stresschemical vapor deposition process. The Si₃N₄ layer on the front side ofthe wafer was then lithographically patterned to form arrays ofcantilevers. No oxide layer remains on the backside.

Separately, a Pyrex wafer was coated with a 200 nm thick chromium layerand lithographically patterned to form 100 micron rectangular trenches.The Pyrex was etched in a reactive ion etcher, forming 8 micron recessesto allow the cantilevers free movement, and the chromium was thenremoved. The nitrided silicon wafer and the Pyrex wafer were thenelectrostatically bonded, and the back of the Pyrex wafer was scribedinto 1 cm² substrates by a diamond saw. Finally, the silicon wafer wasetched, leaving the nitrided tip arrays attached to the Pyrex. Theresulting cantilever structures were characterized by optical andelectron microscopy (FIG. 3). The measured radius of curvature forfabricated tip arrays was 60 nm±20 nm.

The force constant (k) of a fixed-free cantilever beam with a length,width, and thickness of l, w, and t is given by k=Ewt³/4t (l), under asmall displacement assumption. The term E denotes the modulus ofelasticity of the probe material. The approximate modulus of elasticityis 145 GPa for the thin film of low-stress deposited layer of Si₃N₄. Thecantilevers had measured dimensions of l=45 microns, w=14.5 microns, andt=400 nm, which correspond to a force constant k=0.40±0.10 N/m.Annealing of pen arrays. To induce tip curling away from the cantileverbase, the tip-side of the cantilevers were first coated with a 5 nm Tiadhesion layer and 25 nm Au using a BOC 306 Edwards vacuum evaporatoroperated at a base pressure below 5×10-7 mbar. Subsequently, the penarrays were placed in an oven, held at 300° C. for 2 hr, and then slowlycooled to room temperature at a rate <5° C./min. The degree ofcantilever bending was inspected by optical microscopy andquantitatively measured by SEM. Although annealing the pen arrays at400° C. induced a larger degree of cantilever bending, the hightemperature also resulted in coarsening of the gold grains due toenhanced Au diffusion. Therefore, 300° C. was chosen as the annealingtemperature. Cantilever bending is caused by the different thermalexpansion of gold (α_(Au)=13.8×10⁻⁶° C.⁻¹) and Si₃N₄ (α_(Si) ₃ _(N) ₄=16×10⁻⁶° C.⁻¹). By modeling the gold coated Si₃N₄ cantilevers as abimorph system, the annealing induced curvature, expressed as the radiusof an arc R, can be calculated from equation 2,

$\begin{matrix}{R = \frac{{3\left( {D_{1} + D_{2}} \right)^{2}D_{1}D_{2}E_{1}E_{2}} + {\left( {{D_{1}E_{1}} + {D_{2}E_{2}}} \right)\left( {{D_{1}^{3}E_{1}} + {D_{2}^{3}E_{2}}} \right)}}{6\Delta \; \alpha \; \Delta \; {T\left( {D_{1} + D_{2}} \right)}D_{1}D_{2}E_{1}E_{2}}} & (2)\end{matrix}$

where D is the thickness (D₁=D_(Au)=25 nm; D₂=D_(Si) ₃ _(N) ₄ =400 nm),E is Young's modulus (E₁=E_(Au)=0.8×10¹¹ N m⁻²; E₂=E_(Si) ₃ _(N) ₄=3.8×10¹¹ N m⁻², Δα is the difference in the coefficients of thermalexpansion, and ΔT is the change in temperature. The deflection ordistance moved by the free end of the cantilever d can be represented byd=L²/2R, where L is the length of the cantilevers.

Heating the tips to 300° C. would produce the expected deflection orcurling of 14 microns. However, the experimentally determined value isabout 20-30 microns, which is most likely a result of deviations in thethickness of Au and the Si₃N₄ layers across the entire tip arrays.(Wenzler et al., Review of Scientific Instruments, 67, 4191-4197 (1996).

Ink Coating: The pen arrays were placed inside a sealed metal containerwith ODT (the pen arrays were attached to the cover of the containerwith a piece of double-sticky tape). The container was heated to 70° C.and held for 30 minutes, and then allowed to slowly cool. This vaporcoating process was repeated (typically 2-3 times) until the tips weresufficiently coated with ODT for DPN printing experiments. Importantly,the coated pen array could be used to pattern more than 25 samples overa period of three days without the need of recoating the tips with moreODT ink.

Pen Array Mounting: The pen array was gently placed onto a sacrificialAu-coated SiOx substrate, letting the weight of the tip array (about 100mg, 20 nN/tip) bring all tips into contact with substrate. An epoxycoated magnetic tip holder (1 cm×0.2 cm) was then gently brought down incontact with the Pyrex support of the pen array using the z motors ofthe AFM (FIG. 4, right). Enough pressure was applied using the motors(about 20-50 micron lower than the epoxy-tip array contact point) untilthe epoxy starts spreading to fill the void between the tip holder andthe tip array (FIG. 4). The epoxy was then left to fully harden over aperiod of at least 1 hr. Note that it was important in this example touse a thin film of epoxy, avoiding excess, since epoxy can undergo a1-10% volume shrinkage during polymerization. (Schoch et al.,Thermochimica Acta, 417, 115-118 (2004); Ramos et al, Polymer, 46,3323-3328 (2005), After the epoxy was fully cured, all the tips couldthen be engaged with the substrate by moving the z-motors to the same(±0.2 microns) curing position. Interestingly, tip-substrate contact canbe observed by monitoring the bending-induced change in the opticalreflectivity of the cantilevers (FIG. 5). Note that the Au-coatingenhances tip reflectivity. The exact position of the tip-substratecontact is maintained to within ±1 micron, and over 20 substrates werepatterned by coming back to the same z position. Remarkably, the penarrays could be remounted on the scanner head and used for highresolution patterning. This system provided for successfully patterningover cm square areas after remounting the tip array on the scanner head.Remounting the magnetic tip holder was facilitated by allowing a smallamount of epoxy to mold onto one edge of the scanner head.

Dip Pen Nanolithography: DPN experiments were performed with anNscriptor™ (NanoInk, Inc., Chicago, Ill.) equipped with a 100-micronscanner and closed-loop scan control and commercial lithographicsoftware (DPNWrite, ™DPN System-1, NanoInk, Inc., Chicago, Ill.). AllDPN patterning experiments were carried out under ambient laboratoryconditions without the aid of a clean room (about 30% relative humidity,about 20° C.).

Selective Etching of Au: Etching was performed on DPN-patterned goldsubstrates by immersing in a bath of 13.3 mM Fe(NO₃)₃9H₂O, 20 mMthiourea, 0.3% HCl in octanol saturated nanopure water (15 mL of etchsolution for a about 1 square cm substrate). (Xia et al., Chemistry ofMaterials, 7, 2332-2337 (1995); Geissler et al, Langmuir, 18, 2374-2377(2002); Zhang et al., Nano Letters, 3, 43-45 (2003). The bath was gentlystirred as the substrate was visually inspected for etching (rate about6 nm/min). The color of the substrate changed from yellow to dark blueas the gold was dissolved.

Pattern Characterization. Patterned structures, post etching, werecharacterized by SEM (Leo Gemini 1525), and optical microscopy (ZeissAxiovert 100A inverted microscope, Thornwood N.Y.) equipped with aPenguin 600CL digital camera and StreamPix software. These tools providea relatively high throughput method for evaluating the quality of thepatterned structures. Tapping mode AFM images were collected with aNanoman AFM equipped with a Nanoscope IV controller from Veeco (SantaBarbara, Calif.) with silicon tips (NCH-W, Veeco, spring constant 40N/m) scanned at a rate of 0.5 Hz and set to a pixel resolution of512×512. Gold coated commercial AFM cantilevers (sharpened Si₃N₄, TypeA, NanoInk, Inc.) with a spring constant of 0.05 N/m were used forcontact mode imaging.

Additional Examples of 2D Parallel DPN: Shown below are three additionalexamples that demonstrate the rapid prototyping capability of 2Dparallel DPN reported herein. FIG. 6 shows Au dot arrays spanning nearlythe entire writing range of each cantilever. FIG. 7 shows Au structuresdeveloped from molecular ODT patterns in the form of the characters “2DDPN.” Each pen generated five structures occupying an area of 9×7microns with a total patterning time of 9 min. FIG. 8 shows Austructures in the shape of nine triangle, four lines, 5×5 dots, and a“smiley face” occupying four quadrants of the patterning area of eachpen. The total patterning time in this case was about five minutes. Notethat these structures are just two examples and virtually any patterngeometry can be generated.

Apex height was measured for a pyramidal tip as shown in FIG. 9.

FIG. 10 shows how distance of bending and angle of bending was measuredwhen the cantilevers are bent at an angle from their base and thecantilevers are bent at an average distance.

All references cited herein are hereby incorporated by reference intheir entirety.

1.-60. (canceled)
 61. A method of making article, wherein the articlecomprises a two-dimensional array of a plurality of cantilevers, and asupport for the array, the method comprising: forming a two dimensionalarray comprising a plurality of cantilevers comprising tips at theirends, wherein the cantilevers are supported on a sacrificial supportstructure; forming an array support comprising a plurality of base rowswhich are adapted for bonding to the two dimensional array comprising aplurality of cantilevers; bonding the cantilevers to the base rows; andremoving the sacrificial support structure to release the cantileversand form the array.
 62. The method according to claim 61, wherein thearray is adapted to prevent substantial contact of non-tip components ofthe array when the tips are brought into contact with a substantiallyplanar surface.
 63. A method according to claim 61, wherein the tipshave an apex height relative to the cantilever of at least four microns.64.-65. (canceled)
 66. A method according to claim 61, furthercomprising the step of bending the cantilevers at an angle of at least10° away from the support.
 67. A method according to claim 61, whereinthe tips have an apex height relative to the cantilever of at least 4microns, and wherein the cantilevers are bent at an angle away from thesupport.
 68. (canceled)
 69. A method according to claim 61, wherein thearray is characterized by a cantilever yield of at least 95%.
 70. Amethod according to claim 61, wherein the array is characterized by atip spacing of less than 200 microns in one dimension and a tip spacingof less than 50 microns in a second dimension.
 71. A method according toclaim 61, wherein the number of cantilevers is greater than 10,000. 72.A method according to claim 61, wherein the base rows have an averagelength of at least about 1 mm.
 73. A method according to claim 61,wherein the cantilevers comprise multiple layers adapted for bending ofcantilevers.
 74. A method according to claim 61, wherein the cantileversare coated with metal on the tip side of the cantilever.
 75. A methodaccording to claim 61, wherein the cantilevers are not adapted for forcefeedback.
 76. A method according to claim 61, wherein the base rows havea height with respect to the support of at least about 5 microns.
 77. Amethod according to claim 61, wherein the tips have an average radius ofcurvature of less than 100 nm.
 78. A method according to claim 61,wherein the cantilevers have an average force constant of about 0.1 N/mto about 1 N/m.
 79. (canceled)
 80. A method according to claim 61,wherein the cantilevers are bent on average about 10 microns to about 50microns.
 81. A method according to claim 61, wherein the bonding step isa non-adhesive bonding.
 82. (canceled)
 83. A method according to claim61, wherein the forming of the two dimensional array comprisesmicrofabrication.
 84. A method according to claim 61, wherein theforming of the array support comprises microfabrication.
 85. A methodaccording to claim 61, wherein after the bonding step, the array supportis scribed into sections about 2 square cm or less. 86.-104. (canceled)